Yes I did all kind of tests nothing worked. We have 2 different PC's where LR6.8 is running and on both we have the same problem. When trying to make a video with the same audio and jpg files with a LR5.7 on a 3rd machine there is no problem :-(

It doesn't work in my case. Do you have any idea what is the problem? If yes, can you tell us any forecast of troubleshooting? If you haven't located the problem, how does it work usually in similar cases?